Method of reconditioning refrigerating apparatus and reclaiming refrigerant



Feb. 8, 1944. H. M. ELSEY 2,341,430

METHOD 0F RECONDITIQNING RBFRIGERATING APPARATUS AND RECLAIMXNG REFHIGERANT Filed July 19, 1941 PEPE/GERANT STPA INEP 6.1+. r I BY ATTOR reams Feb. 8. 1944 UNITED STATES PATENT OFFICE METHOD OF ATING APP FBIGEBANT Howard M.Eisey,

inghouse Electric in East Pittsburgh, Pa

sylvania CONDITIONING REFRIGER- ARATUS AND BECLAIMING RE- Oakmont, Pm, asdguor to West- Manufacturing Company,

a corporation of Penn- Application July 19, 1941, Serial No. 403,114 2 Ciaims. [CL 62-170) a number of gases such as carbon dioxide, carbon monoxide and methane. The oil reacts with the refrigerant, to form among other substances, hydrochloric acid gas and hydrogen fluoride gas, the acid gases combining with the water from the cellulose to form acid water solutions, which attack the metals of the system and quickly lead to valve failures, due to embrittlement of the hardened steel plate.

According to one method that has been tried, the crankcase and housing of a motor-compressor unit, in which the stator failed, were cleaned mechanically and by washing with kerosene. The stator was replaced, and the refrigerant and oil were replaced with new material. The unit was then run and this "rinsing charge of refrigerant and oil was replaced with another charge of new materials. This method, however, did not reduce the contamination to an amount considered suillciently low for continued satisfactory operation.

In my application, Serial No. 348,278, filed July 19, 1940, I disclosed a method of reconditioning a refrigerating system in which method the refrigerant is circulated in contact with a mixture including an absorbent, which is preferably cocoanut charcoal but which may be fuller-s earth, activated alumina or silica gel. and a drylng agent which is preferably calcium oxide but which may be activated alumina.

Theresultsofthemethodusingsuch mixture have been good. However, calcium oxide has a disadvantage in one respect. when it reacts with water. the calcium hydroxide which isformed is a palpable powder.

In accordancewith the present invention, 1 provide a mixture which includes (1) anhydrous ulcium sulfate, (2) an acid neutralising or reacting substance, such as calcium carbonate. or possibly calcium oxide, and (3) an armor-bent, whiohiepteferablycoeoanutcharcoabforremoving system having a reclaimer assembly conremainder of the refrigerating system,

ing other deleterious substances formed when a stator is burned out in the presence of lubricating oil and a refrigerant containing fluorine or chlorine.

The above-recited and other objects are effected by my invention as will be apparent from the following description and claims taken in connection with the accompanying drawing forming a part of this application, in which:

Fig. 1 is a diagrammatic view of a refrigeratnected therein;

Fig. 2 is a vertical sectional claimer.

Referring to the drawing in detail, the refrigerating system comprises an evaporator Ill, a motor-compressor unit li, a conddenser II, which also serves as a liquid receiver, and an expansion valve I. In addition, the refrigerating system includes a suction conduit ll, suction and discharge valves I! and Ill whereby the motor-compressor unit may be isolated from the adlscharge be provided with a muf- -view of the reconduit I! which may fler it, a shut-oi! valve prising a conduit 2| which is shown in Fig. 1 as replaced by the reclaimer assembly, arefrigerant strainer 12, a shut-oi! valve 23, a conduit 24, a second refrigerant strainer II, and a conduit 28. The parts are connected to form a complete refrigerant circuit, as will be fully apparent from the drawing and as is well understood. in the art.

The evaporator Hi is shown diagrammatically since the invention is not dependent upon any particular formof evaporator, but in actual practice it may be any one of the several commercial forms of evaporator. It may serve any desired cooling purpose, for example, it may cool a stream of air flowing thereover.

The motor-compressor unit II is of the enclosed type. comprising a compressor 21 and a motor 18 for driving the compressor, the motor including a stator IS. The motor-compressor unit includes a casing 3! which forms a common housing or casing for the compressor and the motor. The motor II is, therefore, enclosed in an atmosphere of refrigerant vapor. In the illustrated embodiment, the vaporized refrigerant is conveyed from the suction conduit ll through the portion of the casing Ii containing the motor, so that the latter is cooled by direct contact of the refrigerant vapor easing It includes a portion forriiing a crankcase II provided with a removable side plate II,

is, and a liquid line com-- therewith The whereby access may be had to the crankcase.

tutes a reservoir for a body of oil for lubricating the motor-compressor unit, the oil, whose level is indicated at 34, extending into the motor-containing portion of the casing so that the lowermost portion of the stator 29 is immersed in the oil and at least a portion of the stator is oil-soaked.

The condenser I2 comprises a drum 35 and coils 38 therein through which cooling water is circulated for condensing the compressed refrigerant. The condensed refrigerant collects in the bottom of the drum so that the latter also serves as a liquid receiver. The expansion valve I3 may be of any suitable type known in the art, for example, it may be of the type known as a thermostatic expansion valve, which regulates the flow of refrigerant to the evaporator in response to the opposed efiects of the pressure and the temperature of the refrigerant discharged i'rom the evaporator and serves to maintain the superheat thereof substantially constant.

There is connected into the refrigerating system, as shown in Fig. 1, a reclaimer assembly comprising a reclaimer 31, a filter 38 and connecting conduits 39, 40 and 4|. The reclaimer 31, shown in greater detail in Fig. 2, includes a container which may comprise a cylindrical shell 42 and covers 43 at the ends thereof. Within the container there is provided a mixture of an absorbent, a drying agent, and an acid reacting substance, all of which are preferably in the form of small particles or granules and thoroughly mixed with each other. This material is held within the container in spaced relation to the covers 43 by means of screens 44, which may be retained in place in any suitable manner, for

example, by rings "and shoulders in the shell 42, as shown in Fig. 2. The conduits 39 and 40 preferably project through the covers 43 and abut against the central portions of the screens 44, serving to hold the same against the material between the two screens. These conduits are preferably provided with openings 8 to provide communication with the chambers between the covers 43 and the screens 44. I

The absorbent provided in the reclaimer 31 may be of any suitable material which will remove such compounds as the tars, carbon dioxide, carbon monoxide, and acetone. It may be, for example, fullers earth, cocoa-nut charcoal, activated alumina, or silica gel. I prefer to use cocoanut charcoal. The drying agent provided in the reclaimer 37 is anhydrous calcium sulfate. The acid reacting agent is preferably calcium carbonate, although it may be calcium oxide, or calcium hydroxide.

Operation In the normal operation of the refrigerating apparatus, the reclaimer assembly is omitted and replaced by the conduit II, which is soldered to the shut-off valve I9 and bolted to the strainer 22. The refrigerating apparatus operates in the usual manner of apparatus of this type, the circulation of refrigerant being effected by the compressor 21 driven by the motor 28. The refrigerant vaporized in the evaporator Ill by the heat extracted from the air flowing over the evaporator, flows through the suction conduit ll, the valve I and the motor-containing portion of the casing 3| to the compressor 21, which raises the pressure of the refrigerant gas. The compressed refrigerant is conveyed through the discharge valve I6, the discharge conduit I1, and the muflier I8 to the condenser I2, wherein it is condensed and collected in the bottom thereof. The liquid refrigerant then flows through the valve iii, the conduit II, the strainer 22, the valve 23, the conduit 24, the strainer 25, and the conduit 26 to the expansion valve I3, which regulates the flow of refrigerant to the evaporator and reduces the pressure thereof. From the expansion valve, the refrigerant is admitted to the evaporator I0, again to serve for cooling the air flowing thereover.

Due to any one of several causes, the refrigerant within the system may become contaminated. For example, should the stator 29 be burned out, due to any one of several reasons, a variety of compounds may be formed, as mentioned above.

In accordance with my invention, the refrigerating system is reconditioned and the refrigerant is reclaimed as follows: If the motor 28 is operable, as is the case when the stator 29 has already been replaced, the refrigerating system is pumped down, that is, the refrigerant is pumped into the combined condenser and liquid receiver I2. This is done by operating the motor-compressor unit with the valve I9 closed, so that the low-pressure side of the system, including the interior of the motor-compressor unit, is substantially evacuated and the refrigerant is collected, primarily in liquid form, in the condenser and liquid receiver it. The suction and discharge shut-oil valves l5 and I6 are then closed to isolate the motor-compressor unit from the remainder of the system.

If the stator has been burned out and has not been replaced, the unit is isolated by closing the valves l5 and it without first pumping down the system. In either case, the oil is drained from the crankcase and the latter is opened by removing the side plate 33, the refrigerant within the unit being vented to the atmosphere. The crankcase. is then cleaned of solid and semisolid impurities by mechanically cleaning the same, as by scraping. The crankcase and the casing are then washed out with kerosene or other suitable solvent. The stator 29 is replaced, if necessary. The side plate 33 is then replaced, and a fresh charge of lubricating oil is admitted to the unit. The reclaimer assembly is connected into the refrigerant circuit between the valve I9 and the strainer 22. as shown in Fig. 1, the conduit II being removed during this time. Th reclaimer and the filter are disposed vertical] as shown. The refrigerating system, other than the condenser i2, is then evacuated in any suitable manner, as is well understood in the art. This maybe done; for example, by operating the compressor 21 and also operating a vacuum pump connected to the discharge side of the compressor. When the evacuation is completed, the vacuum pump is disconnected and the shut-off valves opened. The compressor is then operated to circulate refrigerant through the system for a predetermined period of time, preferably fortyeight hours.

During this operation, refrigerant is circulated through the system, including the reclaimer assembly, in substantially the same way as in normal operation. The condensed refrigerant flows through the reclaimer 31 and the filter 38. In the reclaimer 31, the liquid refrigerant flows through the openings 45 and the screen 44 and then through the mixture comprising anhydrous calcium sulfate. calcium carbonate and cocoanut charcoal. The anhydrous calcium sulfate effectively removes the water from the refrigerant. It has no neutralization properties for such acids as hydrogen chloride and hydrogen fluoride. These acids react with the calcium carbonate to form calcium chloride or fluoride and carbonic acid. Calcium chloride is not a basic oxide and will not react.with dichlorodifluoromethane. Carbonic acid is very unstable and dissociates to yield water, which will react with the calcium sulfate in the mixture, and carbon dioxide which is a non-condensable gas that can he removed from the refrigerating system by a process of bleeding such as is used to remove residual air and other, non-condensable gases present in such a system, as is well-known in the art. The cocoanut charcoal removes by adsorption other undesirable organic decomposition products which do not react with calcium sulfate or calcium carbonate.

During this period of 48 hours operation. the refrigerant is preferably circulated through the entire refrigerant circuit. as in the illustrated embodiment. Where there are several motorcompressor units and it is not feasible to operate all of them at the same time, then the same procedure should be carried out for each motorcompressor unit. Also when applying the pres ent method to a refrigertaing system having a liquid receiver or other refrigerant-containing portion normally out out of active circulation, as in the case of the known type of refrigerating system which includes an evaporative condenser and which is critically charged to provide liquid subcooling in a portion of the condenser, the following modification in the method is preferably made: The refrigerating system is operated for a period of 40 horas with the normally inactive portion cut out of circulation. The valves are permit circulation through the normally inactive portion andto remove impurifrom the isdrsinediromthe If'theoilshows aluindlcatlmo! H HM (dirtybrown eoioncdonorcthsrwhc ),theeascrankcase, is

Afterthecasinsisssalnwashedoutandthe side plate 33 replaced. it is evacuated with a vacuum pump and a new charge of oil is admitted to the crankcase, the vacuum being preferably used to draw in the oil. The crankcase is preferably purged with refrigerant. All of the shutof! valves are then opened. and the compressor is operated for an additional two hours.

The system is again pumpe down in the usual manner and the reclaimer assembly is removed. The conduit Ii is replaced, being soldered to the The refri erant circuit is then tested for leaks and, if necessary, the conduits are evacuated with a. vacuum pump.

The system is then restored to normal operation by opening all valves and operating the same for a short period of time to make certain that it is in proper operating condition.

While I have shown the reclaimer as connected in the liquid line to contact the refrigerant while in the liquid state, I desire it to be understood that it may be connected in a portion of the clrcult, such as the suction line, in which the refrigerant is in the form of a vapor. This is sometimes desirable in the case of a critically charged system. such asone including a capillary tube expansion device.

What I claim is: i

i. The method of reconditioning a refrigerating system comprising a.motor-compressor unit having a fluid-tight casing, the stator of which has burned out in the presence of a hydrocarbon lubricant and a refrigerant, which method comprises cleaning the interior of the casing, removing the burned-out stator and replacing it with another stator and then operating the compressor to circulate refrigerant through the refrigerating system and in such circulation conveying the refrigerant in contact with adsorbent charcoal. calclum sulfate and a calcium compound which 

